Author Topic: ROV - Project underway  (Read 22075 times)

  • Offline zpyder

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ROV - Project underway
on: September 08, 2013, 21:19:52 PM

Frame by Chris_Moody, on Flickr

Frame is built. Camera in the mail. Just sourcing the electronic parts.

Decided to drill holes in each of the connecting pieces on the tubing. Intention is to cable tie everything together. This way, if at a later date something needs changing, I can do it fairly easily. Plus, the tubing is polypropylene, and not PVC, so solvent weld doesn't work D'OH!

Tomorrow I'll be popping to a local chandlery to see if they can do any cheap bilge pump motors. I also have to sort out the floats, which are currently "curing" outside (milliputted some end caps onto some larger diameter tubing to seal them).

Then it'll be a case of figuring out the best wiring solutions for the motors, and how to handle the GoPro+WiFi set up. I'm tempted to try and improve the simple flick-switch toggles in the Bucket ROV guide, and get something that at least has an intermediate power setting. I'm thinking more powerful bilge motors (guide reckons 500gallons an hour, I'm thinking 1000). If I can control the motor speed, it'll give me the option in the water to maintain a steady pace/speed, or a burst of power etc.

Re: ROV - Project underway
Reply #1 on: September 09, 2013, 06:11:42 AM
Have you checked the range of WiFi underwater? At 2.4ghz it's microwave which has absolutely crap transmission through water.

Hell that's how it is used for cooking. I've a suspicion that your lucky if it's a few feet.

Sent from my Nexus 4 using Tapatalk 2

  • Offline zpyder

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Re: ROV - Project underway
Reply #2 on: September 09, 2013, 09:26:13 AM
The plan is to encase a small Netgear WNCE2001 repeater in resin and situate it as close to the camera as possible, IE, <2cm if possible. This will be linked by ethernet in the tether to a router on the surface, which will connect to an android tablet running the GoPro App, allowing live video feed.

It can be done ;)

Opting for this, rather than a CCTV type of setup, as the picture quality will be better, I can use the camera for other things, and not having any cables going in or out of the camera housing will mean that there is much less chance of the camera flooding.

  • Offline zpyder

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Re: ROV - Project underway
Reply #3 on: September 09, 2013, 10:10:13 AM
Doesn't bode well...

Quote
09/09/2013   10:00   Goods Not Received At Del Depo   Poole   1
09:16   Hub Mis-Sort   Poole   1
07/09/2013   05:00      Poole   1
05:00   Goods Not Received At Del Depo   Poole   1
04:56   Items Tracked   Worcester   1
06/09/2013   21:38   Items Tracked   Marston Gate Southern Hub   1
16:46   Consignment data received   Croydon   1
16:32   Items Tracked   Croydon   1

Re: ROV - Project underway
Reply #4 on: September 09, 2013, 11:58:52 AM
are you going to have the batteries fixed to the ROV or up at the surface ?

you can get DC speed controllers for pretty cheap (about £10 each iirc)

only problem is you might need to boost the power down to them, because the signal from your controls will only be low voltage, and there'll be some voltage loss over the length of your cable, it's not a big deal tho, you can fix it by using a small resistor to send power down the cable all the time.. just enough to cancel out the losses
(so if you loose 1.8v down the cable, use a resistor to send 1.7v down it all the time)

the speed controllsrs will need waterproofing, you could just cast those in resin too tho


what's your plan for batteries ?  I've got about 6,000 used laptop cells here, I could send you some if you like ? (lithium iron, foc)


EDIT:
these are the controllers I was thinking about....
http://www.ebay.co.uk/itm/FREE-POST-Electric-Controller-24V350W-E-Bike-Scooter-Brushed-DC-Motor-Controller-/140928015431?pt=UK_Sporting_Goods_Scooters_LE&hash=item20cff6dc47

but I've just realised you'll need 2 for each motor, one for forwards and one for backwards, small/cheap controllers don;t do reverse :-(
Last Edit: September 09, 2013, 12:05:26 PM by knighty #187;

  • Offline zpyder

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Re: ROV - Project underway
Reply #5 on: September 09, 2013, 15:14:52 PM
Figured the easiest option would be to use a 12v car charger battery type jobby on the surface. Less things to waterproof that way.

Something like this:

http://www.screwfix.com/p/ring-automotive-power-pack-jump-starter-12v/38140#product_additional_details_container

There might be some power loss down the line, but that should be ok for the motors (doesn't matter if they aren't running at 100% power I guess) - the router might have issues, but only needs 5v to power it, so it depending on how much power is lost down the line, I might put a 12->5v dc dc converter down there next to the wireless point.
Last Edit: September 09, 2013, 16:30:55 PM by zpyder #187;

  • Offline zpyder

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Re: ROV - Project underway
Reply #6 on: September 09, 2013, 15:19:22 PM
Thanks for the link about the motor controller.

I was thinking something more like this:

http://www.musiclily.com/musiclily-5-way-pickup-selector-toggle-switch-black-m192.html&currency=GBP&language=en?gclid=CP-JuOnAvrkCFYPHtAodXz4AIw

Middle point being off, the far points being "on", and the intermediate points being connected to some kind of transformer/resistor to reduce the power going to the motors? Bit cheaper than your option if its doable?

EG
Full + power / 50% + power / Neutral(off) / 50% - Power / Full - Power
Last Edit: September 09, 2013, 16:31:58 PM by zpyder #187;

  • Offline zpyder

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Re: ROV - Project underway
Reply #7 on: September 09, 2013, 16:36:39 PM
SO FAR:

Frame built
Pontoons to be worked on in a bit
Camera has been sent to the wrong Depot by FedEx and will turn up tomorrow (hopefully)
30m Ethernet cable ordered
100m dual core speaker cable ordered

Bilge pump motors are proving tricky to source. Lots out there, but there seems to be a massive price difference between the UK and USA (nothing new there) and designs. Over here it seems to all be about whole pump assemblies. American stuff seems to be much more modular with replaceable parts.

Once the wiring, router and camera turn up I'll probably sort out the power source and switches. THEN, I should be good to try and put it together :D

Re: ROV - Project underway
Reply #8 on: September 09, 2013, 19:55:59 PM
the problem with a resistor etc.. if that any time a motor is on, even if it's only going slow you'll still be using full power (and dumping the excess as heat) so you'll work through your battery pretty quick

you could get 24v pumps, and then use 6 volt batteries so you could run them at 6v/12v/18v/24v for different speeds.... but then the problem is you need to run 5 power wires down to the rov to power it

I'll have a hunt around as see if I can find any better motor controllers, how many motors will you be running ?
also, I've thought of a way to cheat to do reverse, so you only need one controller per motor

will you be running it from land or from a boat ?

500watts at 12v is 41amps... at that power level a big car battery would last about an hour before it starts to die and an hour and a half till it's dead (if you're lucky)

wait... 500watts is a lot for a bilge pump... did you mean a 500gal/hour not watts ?

Re: ROV - Project underway
Reply #9 on: September 09, 2013, 19:57:20 PM
http://www.ebay.co.uk/itm/BILGE-PUMP-SUBMERSIBLE-1100-GPH-12V-new-and-boxed-/180993395164?pt=UK_CarsParts_Vehicles_BoatEquipment_Accessories_SM&hash=item2a240c09dc

these no good ?

they're designed so the water it's pumping moves up around the motor (to cool it) and then out - you can just cut away most of the white plastic and you'll be left with the motor sticking with a shaft on the end for the propeller ?

(p..s my 3d printer should be here soon if you'd like propellers or other parts printing :-) )

  • Offline zpyder

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Re: ROV - Project underway
Reply #10 on: September 09, 2013, 20:12:12 PM
Yeah saw those in a shop today. The motor cartridge was a bit too embedded for my liking (To cut away the plastic to get enough clearance for a propeller to get attached, looked like I'd compromise the waterproofing)

I've found some bilge motors that the cartridges come out of,so that part is all good, and yes, it was gallons per hour, not watts!

3 motors. Left, Right, and Up/down. The 3 way switch is so that you can reverse the current and go in reverse. I ended up getting two 700gph and a 800gph motor. The more powerful one is for up/down control. Have thought that a future design mod would be to add an additional up/down, and have one at the front and one at the back. This would give a degree of tilt. If it ever got that far, I'd probably then start to look into some of the uber cool joystick controller options I've seen...

Will be running from land and boat. I foresee it mostly getting used in and around marinas and quaysides to inspect the fouling organisms on the pontoons and boats. However there'd probably be an opportunity to use it on the local surf reef.

Might take you up on the offer of 3D printed bits too ;)

Re: ROV - Project underway
Reply #11 on: September 09, 2013, 20:32:54 PM
the problem with a resistor etc.. if that any time a motor is on, even if it's only going slow you'll still be using full power (and dumping the excess as heat) so you'll work through your battery pretty quick


That's not the case, the more resistance the less power usage (P=V^2/R) to the point where resistance is infinity and no power is drawn, you'll lose a bit to heat, but not significant.

Also if you are looking to control the motor, why not something like this, giving you full range rather than stepped and fairly easy? http://www.allaboutcircuits.com/vol_6/chpt_3/7.html

Or one of these, as they are designed for 12V :) http://www.ebay.co.uk/itm/Greenhills-Scalextric-Hand-Controller-Red-/200934225135

And use this circuit to reverse polarity, you could also mount this in the controller:


Re: ROV - Project underway
Reply #12 on: September 09, 2013, 20:40:56 PM
In response to your joystick post, you could just use an arcade joystick to control the forwards/backwards/left/right, and a power controller as above to control speed..

http://www.ebay.co.uk/itm/Red-Ball-8-Way-Joystick-Fighting-Stick-Parts-for-Game-Arcade-/261063136770?pt=UK_Video_Games_Coin_Operated_MJ&hash=item3cc8935602

  • Offline zpyder

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Re: ROV - Project underway
Reply #13 on: September 09, 2013, 20:49:08 PM
Must admit I like the idea of the Scalextric controllers, and the arcade joystick :D

Re: ROV - Project underway
Reply #14 on: September 09, 2013, 20:59:14 PM
Providing you got a joystick with SPDT (the one I linked wasn't) details below:

http://www.homebuiltrovs.com/howtojoystickhbridge.html

the rest of the site might be of some use too :)

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